page_title: Kyanite
section_title: Notes for identification
hierarchical_section_title: Kyanite / Notes for identification
caption_attribution_description: English: Kyanite
context_page_description: Kyanite is typically a blue aluminosilicate mineral, usually found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. Kyanite in metamorphic rocks generally indicates pressures higher than four kilobars. It is commonly found in quartz.
  Although potentially stable at lower pressure and low temperature, the activity of water is usually high enough under such conditions that it is replaced by hydrous aluminosilicates such as muscovite, pyrophyllite, or kaolinite. Kyanite is also known as disthene, rhaeticite and cyanite.
  Kyanite is a member of the aluminosilicate series, which also includes the polymorph andalusite and the polymorph sillimanite. Kyanite is strongly anisotropic, in that its hardness varies depending on its crystallographic direction. In kyanite, this anisotropism can be considered an identifying characteristic.
  At temperatures above 1100 °C kyanite decomposes into mullite and vitreous silica via the following reaction: 3 → 3Al₂O₃·2SiO₂ + SiO₂. This transformation results in an expansion.
  Its name comes from the same origin as that of the color cyan, being derived from the Ancient Greek word κύανος.
context_section_description: Kyanite's elongated, columnar crystals are usually a good first indication of the mineral, as well as its color (when the specimen is blue). Associated minerals are useful as well, especially the presence of the polymorphs of staurolite, which occur frequently with kyanite. However, the most useful characteristic in identifying kyanite is its anisotropism. If one suspects a specimen to be kyanite, verifying that it has two distinctly different hardness values on perpendicular axes is a key to identification; it has a hardness of 5.5 parallel to {001} and 7 parallel to {100}.
caption: Deep blue kyanite
exif: {"Image ImageDescription": "SONY DSC", "Image Make": "SONY", "Image Model": "DSLR-A300", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS4 Windows", "Image DateTime": "2010:12:23 20:15:53", "Image YCbCrPositioning": "Co-sited", "Image PrintIM": "[80, 114, 105, 110, 116, 73, 77, 0, 48, 51, 48, 48, 0, 0, 6, 0, 1, 0, 22, 0, ... ]", "Image ExifOffset": "372", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1050", "Thumbnail JPEGInterchangeFormatLength": "4123", "EXIF ExposureTime": "1/100", "EXIF FNumber": "63/10", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "100", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2010:12:23 14:03:46", "EXIF DateTimeDigitized": "2010:12:23 14:03:46", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "8", "EXIF BrightnessValue": "178/25", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "497/100", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Tungsten (incandescent light)", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "55", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3872", "EXIF ExifImageLength": "2592", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "924", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Manual", "EXIF FocalLengthIn35mmFilm": "82", "EXIF SceneCaptureType": "Standard", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal"}